1 files changed, 2 insertions, 0 deletions

diff --git a/src/microhttpd/response.c b/src/microhttpd/response.c
index a77dbe27..4ae46bf3 100644
--- a/src/microhttpd/response.c
+++ b/src/microhttpd/response.c
@@ -951,8 +951,10 @@ MHD_response_execute_upgrade_ (struct MHD_Response *response,
   struct MHD_UpgradeResponseHandle *urh;
   size_t rbo;
 
+#ifdef MHD_USE_THREADS
   mhd_assert ( (0 == (daemon->options & MHD_USE_INTERNAL_POLLING_THREAD)) || \
                MHD_thread_ID_match_current_ (connection->pid) );
+#endif /* MHD_USE_THREADS */
 
   if (0 == (daemon->options & MHD_ALLOW_UPGRADE))
     return MHD_NO;